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This image shows rainfall totals for the period Aug. 21 to 27, 2012, when Isaac formed and tracked through the northern Caribbean and past south Fla. The most significant rainfall over land in the northeast Caribbean occurred over southwest Haiti and the southern coast of the Dominican Republic where between 120 to around 200 mm (~5 to 8 inches, shown in green and yellow) fell. Prior to Isaac, an upper-level low brought heavy rains over southeastern Florida. The combination of the two resulted in totals over 160 mm (~6 inches, shown in bright green) in central Fla. to as much as 320 mm (~13 inches, shown in purple) over Lake Okeechobee.Credit: NASA/SSAI, Hal Pierce
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This image shows rainfall totals from Aug. 27 to Sept. 5, 2012 when Isaac came ashore in southeast Louisiana and moved up into Missouri. Southeast Louisiana, southeast Mississippi, western Alabama, and southeast Florida saw rainfall totals anywhere from 120 mm to upwards of 320 mm. Rainfall totals on the order of 40 to as much as 120 mm (~2 to 5 inches, shown in blue and green) spread across northern Missouri, Illinois, Indiana and Ohio.Credit: NASA/SSAI, Hal Pierce
NASA Analyzes Isaac's Rainfall: Drought Relief and Flooding

As it passed through the northern Caribbean, around south Florida, and into Louisiana and the Middle Mississippi Valley, Hurricane Isaac brought lots of rain, some of it beneficial, and some of it not. Using data from the TRMM satellite, NASA created images of rainfall totals generated along Hurricane Isaac's path.

In addition to capturing detailed images of tropical storms, the Tropical Rainfall Measuring Mission (TRMM) satellite is ideally suited to measure rainfall from space. TRMM is managed by NASA and the Japanese Space Agency, JAXA. For increased coverage, TRMM is used to calibrate rainfall estimates from other satellites. The TRMM-based, near-real time Multi-satellite Precipitation Analysis (TMPA) at the NASA Goddard Space Flight Center in Greenbelt, Md. is used to estimate rainfall over a wide portion of the globe.

TMPA rainfall totals for the period August 21 to 27, 2012 were compiled. During the time, that Isaac formed and made its way through the northern Caribbean and past south Florida. The highest totals for the period are over the waters of the northeast Caribbean and parts of the central and eastern portion of the Florida peninsula in and around Lake Okeechobee. The most significant rainfall over land in the northeast Caribbean occurred over southwest Haiti and the southern coast of the Dominican Republic where between 120 to around 200 mm (~5 to 8 inches) fell.

Unfortunately, the storm caused extensive flooding in Haiti and was blamed for 24 fatalities, while the neighboring Dominican Republic reported 5 fatalities. Rainfall totals were also on the order of 120 to 200 mm along the coast of northern Cuba, but over Florida, the totals were much higher. Prior to the rain from Isaac, an upper-level low spawned numerous showers and thundershowers over southeastern Florida. The combination of the two resulted in totals over 160 mm (~6 inches) in central Florida to as much as 320 mm (~13 inches) over Lake Okeechobee.

Another image was created that showed TMPA rainfall totals from Aug. 27 to Sept. 5, 2012 when Isaac came ashore in southeast Louisiana and moved up into Missouri. The highest totals over land for this period were in southeast Louisiana, southeast Mississippi, western Alabama, and southeast Florida with totals anywhere from 120 mm to upwards of 320 mm (~5 to 12.6 inches).

Locally, New Orleans reported up to 508 mm (20 inches) of rain. Isaac was blamed for five fatalities in Louisiana and two in Mississippi. Farther north, however, Isaac did help to bring some beneficial rains to parts of the drought-stricken Midwest with rainfall totals on the order of 40 to as much as 120 mm (~2 to 5 inches) spread across northern Missouri, Illinois, Indiana and Ohio where the remnants of Isaac merged with a stationary front draped across the region.

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NOAA's GOES-13 satellite captured an image of Isaac's huge blanket of clouds over the U.S., large Tropical Storm Leslie headed to Bermuda (Leslie is about 400 miles in diameter), and very small Tropical Storm Michael far to the east of Leslie, and located in the central Atlantic. The larger system north of Leslie is a cold-core, low pressure system.Credit: NASA GOES Project
Newborn Tropical Storm Michael Struggling Like Leslie and Isaac

Tiny Tropical Storm Michael formed today, Sept. 4, from the thirteenth tropical depression in the Atlantic Ocean, but it seems that wind shear will make Michael struggle to intensify over the next couple of days like his "sister" Tropical Storm Leslie. Isaac's remnants blanket the U.S. east coast.

Leslie has been a tropical storm since late Aug. and has not yet reached hurricane strength because of wind shear, although that is expected to change. Isaac's remnants are also struggling, but struggling to get off the land and back into the Atlantic Ocean. Isaac's remnants are now associated with a stationary frontal system over the U.S. east coast. The storm made landfall in Louisiana as a hurricane on Aug. 29.

NOAA's GOES-13 satellite captured an image of Isaac's huge blanket of clouds over the U.S., large Tropical Storm Leslie headed to Bermuda (Leslie is about 400 miles in diameter), and very small Tropical Storm Michael far to the east of Leslie, and located in the central Atlantic. Michael is more than seven times smaller than Leslie, as tropical-storm force winds only extend out 35 miles (55 km) from the center, making Michael about 70 miles in diameter. The image was created by the NASA GOES Project at NASA Goddard Space Flight Center in Greenbelt, Md.

On Sept. 4 at 11 a.m. EDT, Michael's maximum sustained winds were near 40 mph (65 kmh). Michael was located about 1,220 miles (1,965 km) southwest of the Azores, near latitude 27.0 north and longitude 43.5 west. Michael is moving toward the north-northwest near 5 mph (7 kmh) and expected to move more toward the north in the next couple of days while not strengthening much, according to the National Hurricane Center.

According to NOAA's Hydrometeorological Prediction Center, most of the remnants of Tropical cyclone Isaac are now part of an elongated center of low pressure over the Alabama-Georgia border that is spreading clouds and showers along the U.S. east coast. That center is expected to move south of south-southwest while an upper level low pressure area near Miami moves north-northwestward.

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Tropical Depression Isaac's Remnants continued soaking the Ohio Valley and are moving into the Mid-Atlantic, while Kirk became post-tropical in the northern Atlantic, Tropical Storm Leslie is strengthening and headed north. In the Eastern Pacific, Tropical Depression 10E was born.On Sept. 2 at 7:45 p.m. EDT, the NASA GOES Project created this infrared image from NOAA's GOES-13 satellite that showed all four storms.Credit: NASA GOES Project› View larger image
This visible image from the MODIS instrument onboard NASA's Terra satellite shows the remnants of Tropical Depression Isaac (09L) over the central United States on Aug. 31 at 1 p.m. EDT.Credit: NASA Goddard MODIS Rapid Response Team
NASA Sees Atlantic Storms Isaac, Kirk and Leslie, and E. Pacific TD10E

On Sunday, Sept. 2, Tropical Depression Isaac's Remnants continue soaking the Ohio Valley and are moving into the Mid-Atlantic, while Kirk became post-tropical in the northern Atlantic, Tropical Storm Leslie is strengthening and headed north. In the Eastern Pacific, Tropical Depression 10E was born. All of these storms were captured in one panoramic image created by NASA from NOAA's GOES-13 satellite on Sunday, Sept. 2, 2012

On Sept. 2 at 7:45 p.m. EDT, the NASA GOES Project at the NASA Goddard Space Flight Center in Greenbelt, Md. created infrared image from NOAA's GOES-13 satellite that showed all four storms.

Kirk Becomes Post-Tropical

At 5 p.m. EDT on Sept. 2, Kirk became Post-tropical storm Kirk Hurricane Kirk's with maximum sustained winds near 50 mph (85 kmh). Kirk was about 965 miles (1,550 km) east-northeast of Cape Race, Newfoundland near 49.7 North and 30.1 West. It was speeding to the north 47 mph (76 kmh) and had a minimum central pressure of 1002 millibars. That was the last position noted in the final bulletin from the National Hurricane Center. Additional information on this system can be found in high seas forecasts issued by the United Kingdom Meteorological office.

Tropical Storm Leslie Intensifying Again, Turning North

Tropical Storm Leslie weakened and is now expected to intensify as it turns north. The National Hurricane Center expects Leslie to become a hurricane before reaching Bermuda. On Sept. 2 at 5 p.m. EDT Leslie had maximum sustained winds near 60 mph (95 kmh), and was located about 370 miles (590 km) north of the Leeward Islands, near latitude 22.4 north and longitude 61.3 west. Leslie is moving northwest near 10 mph (17 kmh).

The National Hurricane Center noted that Leslie is generating rough surf that is affecting the Leeward Islands and will begin affecting Puerto Rico and the Virgin Islands during the night on Sept. 2, and during Sept. 3. The GOES-13 satellite imagery indicates strong northwesterly wind shear, where clouds and showers are pushed to the southeast of the center of circulation.

Isaac's Remnants Affecting Ohio and Tennessee Valleys

Isaac is merging with a frontal zone and moving through the Ohio Valley. The remnants associated with a low pressure center were located over Illinois on Sept. 2. East of the low pressure center, the frontal boundary was draped over southern West Virginia and into North Carolina. West of the low, a frontal boundary stretched back through the Tennessee Valley. The low pressure center is expected to crawl eastward over southern Indiana on Sept. 3, and over northern Kentucky on Sept. 4, bringing showers and thunderstorms with it as it crawls east.

At 11 a.m. EDT on Sept. 2, Ileana had become a post-tropical depression with maximum sustained winds near 30 mph (45 kmh). The last advisory from the National Hurricane Center was issued at that time, and Ileana was located near latitude 22.6 north and longitude 122.5 west. The remnant low is moving toward the west near 12 mph (19 kmh). Ileana's remnants are expected to turn west-southwest on Sept. 3. Ileana appears as a large area of clouds to the northwest of Tropical Depression 10E on the GOES-13 satellite image.

Tropical Depression 10E formed 320 miles (510 km) south of the southernmost tip of Baja California at 5 p.m. EDT on Sept. 3. It was centered near 18.3 North and 109.6 West. Tropical Depression 10E had maximum sustained winds near 35 mph (55 kmh) and was moving to the west-northwest at 17 mph (28 kmh). The National Hurricane Center noted that the storm could strengthen into a tropical storm on Sept. 3.

Tropical Depression Isaac is weakening and dropping heavy rainfall along its slow path through the center of the U.S., while Hurricane Kirk is spinning in the central Atlantic, and Tropical Storm Leslie is strengthening on a westward track toward the Caribbean. All of these storms were captured in one panoramic image created by NASA from NOAA's GOES-13 satellite.

On Aug. 31 at 4:45 a.m. EDT, a visible image from NOAA's GOES-13 showed Tropical Depression Isaac centered over Arkansas and moving into Missouri. Hurricane Kirk and Tropical Storm Leslie were moving through the central Atlantic Ocean. The image was created by the NASA GOES Project at the NASA Goddard Space Flight Center in Greenbelt, Md.

Hurricane Kirk Staying at Sea

At 5 a.m. EDT on Aug. 31, Hurricane Kirk's maximum sustained winds were near 105 mph (165 kmh). Kirk was about 835 miles (1,345) east of Bermuda near 30.1 North and 50.9 West. It was moving to the north-northwest 12 mph (19 kmh) and had a minimum central pressure of 970millibars. Kirk is a Category two hurricane on the Saffir-Simpson Scale.

The GOES-13 image showed that Kirk continued to be a compact hurricane, and hurricane force winds extend just 15 miles (30 km) from the center. The National Hurricane Center forecasts Kirk to move in a northeasterly direction over the next four days on an approach to Ireland. As Kirk tracks northward and runs into cooler waters, it will weaken and transition into an extra-tropical storm.

Tropical Storm Leslie Intensifying, Moving West

Tropical Depression 12 formed on Aug. 30, and quickly strengthened into Tropical Storm Leslie. The National Hurricane Center expects Leslie to become a hurricane over the weekend of Sept. 1-2 and move northwest and turn north on Sunday, Sept. 2. Leslie is expected to stay to the north of the Leeward Islands and turn toward Bermuda. At this time, it is expected to pass east of Bermuda.

On Aug. 31 at 6 a.m. EDT Leslie had maximum sustained winds near 65 mph (100 kmh), and was located about 940 miles (1,510 km) east of the Leeward Islands, near latitude 15.2 north and longitude 47.8 west. Leslie is moving west-northwest near 16 mph (26 kmh). Because Leslie continues to move in a favorable environment of low wind shear and warm waters, it could become a major hurricane over the weekend of Sept. 1-2, according to the National Hurricane Center.

Tropical Depression Isaac Over Arkansas and Missouri

At 5 a.m. EDT on Aug. 31, Tropical Depression Isaac had maximum sustained winds are near 25 mph (40 kmh). Isaac is expected to weaken over the weekend of Sept. 1-2 and become a post-tropical remnant low pressure area.

Isaac's center was about 95 miles (155 km) west of Little Rock, Ark. near latitude 34.7 north and longitude 93.9 west. Isaac is moving north near 12 mph (19 km). Isaac is expected to move over Arkansas today and Missouri tonight. Rainfall totals of 3 to 6 inches with isolated maximum amounts of 8 inches possible across Arkansas and into southern Missouri through Friday, Aug. 31. Tornado watches are posted central and southern Mississippi in addition to extreme eastern Arkansas.

Isaac is expected to turn northeast and track over the mid-Mississippi Valley, and into the Ohio Valley on Labor Day, Monday, Sept. 3 as it continues to crawl to the Mid-Atlantic.

Flooding has been widespread in Louisiana, as a result of the heavy rainfall. Following are rainfall totals from Hurricane Isaac, according to the National Hurricane Center:

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TRMM's Precipitation Radar were used to construct these 3D images of Isaac and Katrina. Katrina (on the right) appears as a very symmetrical storm, a sign of a strong circulation, with a well-defined eye (in the center of the cut-away view) surrounded by a complete eyewall containing an area of deep convective towers (shown in red). Isaac (on the left), on the other hand, though surrounded by rainbands that spiral in towards the center is less symmetrical and does not have a distinctive eye though it too has some deep convective towers near its center (shown in red).Image Credit: SSAI/NASA, Hal Pierce
NASA Compares Hurricanes Isaac and Katrina: 7 Years Apart

With Hurricane Isaac making landfall on the northern Gulf coast almost 7 years to the day that Hurricane Katrina made landfall and in almost the same location in southeastern Louisiana that Katrina did, it is natural to compare the two storms.

Katrina of course will always be remembered for the massive storm surge that inundated large portions of the northern Gulf coast, reaching almost 28 feet (8.5 meters) along the Mississippi coast, breaking the previous mark of 24 feet (7.3 meters) left there from Hurricane Camille. Like Katrina, Isaac was also a large storm with both measuring roughly 248 miles (400 km) in size. Big storms have bigger wind fields, which allow them to push against the ocean surface over a large area, increasing the potential for storm surge for a given area of coastline.

Fortunately, Isaac impacted the coast as a much weaker Category 1 hurricane and was a tropical storm prior to that; Katrina made landfall as a much more powerful Category 3 storm and was previously an extremely powerful Category 5 storm. At one point, Katrina had hurricane force winds extending up to 75 miles (120.7 km) from the center. So far preliminary reports indicate that Isaac's storm surge may have reached up to 12 feet in parts of Louisiana, which is quite substantial for a "mere" Category 1 storm. Of course the surge can vary according to the shape of the coastline and seafloor, but 12 feet (3.6 meters) is more in line with a Category 3 storm than a 1 and shows how size can be an important factor.

TRMM's Precipitation Radar (PR) can provide a unique perspective on hurricanes. Data from the PR were used to construct these 3D images of Isaac and Katrina. Katrina (on the right) appears as a very symmetrical storm, a sign of a strong circulation, with a well-defined eye (in the center of the cut-away view) surrounded by a complete eyewall containing an area of deep convective towers (shown in red). Isaac (on the left), on the other hand, though surrounded by rainbands that spiral in towards the center is less symmetrical and does not have a distinctive eye though it too has some deep convective towers near its center (shown in red).

Actually, for most of its life, Isaac lacked a core and only really began to organize and intensify when it neared the coast, which was when the data for this image was collected. Isaac's lack of a core greatly inhibited its intensification and was most likely due to dry air intrusions. This is somewhat evidenced by the gaps in the surrounding precipitation field (visible as the blue and black valleys). Were it not for the dry air entering its circulation, Isaac may have arrived at the Gulf coast looking but much more like Katrina. At the times that the data for these two images were collected by the TRMM PR, Katrina was a rapidly-deepening Category 3 hurricane in the central Gulf of Mexico on its way to Category 5 with sustained winds already at ~115 mph (100 knots) and quickly increasing, and Isaac was a recently-upgraded Category 1 hurricane near the coast of Louisiana with sustained winds of ~80 mph (70 knots).

TRMM is a joint mission between NASA and the Japanese space agency JAXA.

The Tropical Rainfall Measuring Mission (TRMM) satellite's Precipitation Radar (PR) data were used in this August 29, 2012 at 0307 UTC (August 28, 2012 at 10:07 PM CDT) image to show a 3-D view of rainfall within Isaac. A few very powerful thunderstorms near Isaac's eye were reaching heights of almost 17km (~10.6 miles). Those tall thunderstorms near a hurricane's center release heat and can help a hurricane become more powerful. The National Hurricane Center (NHC) reported at 10 PM CDT (close to the time of the first TRMM image) that Isaac's central pressure had fallen to it's lowest value of 968mb (~28.58 inches of mercury). An analysis of rainfall from TRMM's Microwave Imager (TMI) and Precipitation Radar (PR) instruments shows that intense bands of rain around Isaac were occasionally dropping rain at a rate of over 70 mm/hr (~2.75 inches). Due to Isaac's slow movement and intense rainfall, the National Hurricane Center (NHC) expects a prolonged period of flooding in the affected area. TRMM is a joint mission with NASA and JAXA. Credit: NASA/SSAI, Hal Pierce

NASA satellites are providing forecasters with data on rainfall rates within Tropical Storm Isaac as it continues to track over Louisiana, Mississippi and spread northward into the lower Mississippi Valley. Isaac has a large supply of rain, drawing its power from the warm waters of the Gulf of Mexico. NASA's TRMM satellite revealed that some areas within Isaac were dropping rainfall at a rate of 2.75 inches per hour.

The Tropical Rainfall Measuring Mission (TRMM) satellite twice flew directly above Hurricane Isaac as it was starting to pound Louisiana with strong winds and heavy rainfall. TRMM is a joint mission between NASA and the Japanese space agency JAXA.

NASA Measures Isaac's Heavy Rainfall Rates

TRMM's first orbit was on August 28, 2012 at 2212 UTC (5:12 p.m. CDT) and the second time was on August 29, 2012 at 0307 UTC (August 28, 2012 at 10:07 p.m. CDT). Isaac had just made landfall over the Mississippi delta when data used in the first image was captured and was making another Louisiana landfall at the time TRMM flew over Isaac again. An analysis of rainfall done at NASA's Goddard Space Flight Center in Greenbelt, Md. using data from TRMM's Microwave Imager (TMI) and Precipitation Radar (PR) instruments showed that intense bands of rain around Isaac were occasionally dropping rain at a rate of over 70 mm/hour (~2.75 inches).

Due to Isaac's slow movement and intense rainfall, the National Hurricane Center (NHC) expects a prolonged period of flooding in the affected area. The NHC expects Isaac to produce total rainfall amounts of 7 to 14 inches with possible isolated maximum amounts of 25 inches over much of Louisiana., Mississippi, southwest Alabama, and Arkansas through Friday, Aug. 30.

Storm Surges Happening on Aug. 30

According to gauges from the National Ocean Service on Aug. 30 at 8.a.m EDT at New Canal Station, Louisiana a storm surge of near 6 feet was still occurring on the southern shore of Lake Pontchartrain and a storm surge near 5 feet was occurring at Waveland, Mississippi.

Isaac in 3-D Shows Powerful, Towering Thunderstorms

A three-dimensional view of rainfall within then Hurricane Isaac was made at NASA Goddard using TRMM's Precipitation Radar (PR) data. The 3-D image showed a few very powerful thunderstorms near Isaac's eye were reaching heights of almost 17km (~10.6 miles). Those tall thunderstorms near a hurricane's center release heat and can help a hurricane become more powerful. NHC reported at 10 p.m. CDT (close to the time of the first TRMM image) that Isaac's central pressure had fallen to its lowest value of 968 millibars (~28.58 inches of mercury).

Landfall on Hurricane Katrina's Anniversary

Seven years ago on Aug. 29 Hurricane Katrina made landfall in southeastern Louisiana in nearly the same location as did Isaac in 2012. Katrina of course brought a massive storm surge that inundated large portions of the northern Gulf coast, reaching almost 28 feet (8.5 meters) along the Mississippi coast, breaking the previous mark of 24 feet left there from Hurricane Camille. Like Katrina, Isaac is also a large storm measuring roughly 249 miles (400 km) in size, which allows its wind field to push against the ocean surface over a large area, increasing the potential for storm surge for a given area of coastline. Fortunately, Isaac impacted the coast as a much weaker Category 1 hurricane and was a tropical storm prior to that; Katrina made landfall as a much more powerful Category 3 storm and was previously a Category 5 storm. At one point, Katrina had hurricane force winds extending up to 75 miles from the center. So far preliminary reports indicate that Isaac's storm surge may have reached up to 12 feet (3.6 meters) in parts of Louisiana.

Where is Isaac on Aug. 30?

The National Hurricane Center (NHC) bulletin at 8 a.m. EDT on Aug. 30 noted that Isaac had weakened to a tropical storm with maximum sustained winds near 45 mph (75 kmh). Tropical-storm-force winds extend outward up to 175 miles (280 km) mainly east through south of the center. NHC forecasters noted that the strongest winds were occurring over water near the coast during the morning hours on Aug. 30.

Isaac hasn't moved much over the last two days, and continues a slow crawl to the north at 8 mph (13 kmh). At 8 a.m. EDT Isaac was located about 35 miles (60 km) southeast of Alexandria, La. or 125 miles (205 km) northwest of New Orleans, La. near latitude 31.1 north and longitude 91.8 west. NHC forecasters expect Isaac to continue a northerly track and weaken to a tropical depression late on Aug. 30, Thursday.

In addition to the heavy rains, storm surge and tropical-storm-force winds, isolated tornadoes are possible along the central Gulf Coast region and parts of the lower Mississippi River Valley through the day on Aug. 30. According to NHC, on the forecast track, the center of Isaac will continue to move over Louisiana today, over Arkansas on Friday, Aug. 31 and over southern Missouri Friday night.

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NASA's Terra satellite flew over then Tropical Storm Isaac at 11:30 a.m. CDT on Aug. 28, 2012 and this image was captured by the MISR instrument. The motion of the low clouds is counterclockwise, with the strongest winds in the upper part of the image where the motion of the storm couples with the inflow. The motion of the clouds to the southeast of the storm center is clockwise. The imagery shows that these are thin, cirrus clouds characteristic of the storm outflow.Credit: NASA/GSFC/LaRC/JPL, MISR Team
NASA's MISR Instrument Shows Isaac’s Inflow and Outflow

NASA’s Terra spacecraft and its Jet Propulsion Laboratory (JPL)-built Multi-angle Imaging SpectroRadiometer (MISR) instrument flew over then Tropical Storm Isaac at 11:30 a.m. CDT on Aug. 28, 2012, a few hours before Isaac was upgraded to a Category 1 hurricane on the Saffir-Simpson scale. At the time of the overpass, MISR recorded low-level wind speeds of up to 75 miles per hour (65 knots) from cloud motion observed outside Isaac’s eye. The National Hurricane Center in Miami similarly reports maximum sustained winds of 69 miles per hour (60 knots) with gusts to 86 miles per hour (75 knots) soon after. Isaac made initial landfall in southeastern Louisiana in Plaquemines Parish about 90 miles (145 kilometers) southeast of New Orleans around 6:45 p.m. CDT with maximum sustained winds of 80 miles per hour (70 knots).

The MISR image showed the eastern half of the storm from one of MISR's nine cameras. At the time of the overpass, the storm was located in the Gulf of Mexico, southeast of Louisiana. The eye of the storm was just off the western edge of the image, while the coast of the Florida panhandle is located near the top of the image. By tracking the motion of clouds as they move between views from different cameras and taking into account stereo parallax, it is possible to derive both cloud motion and height from MISR data. Derived wind vectors are superimposed on the image. The arrows show both the direction and speed of the wind, and the color scale indicates the height at which the wind is detected.

Hurricanes can be thought of as heat engines that ingest warm, moist air at low levels in the atmosphere, convert it into energy in the form of wind and rain, and then eject cool, dry air at high levels. Due to Earth’s rotation, the low-level air spirals inward in a counterclockwise direction, while the high-level winds move outward from the eye in a clockwise direction. The MISR vector cloud motion retrievals, with a gridded resolution of 11 miles (17.6 kilometers), show this circulation. The motion of the low clouds is counterclockwise, with the strongest winds in the upper part of the image where the motion of the storm couples with the inflow. The motion of the clouds to the southeast of the storm center is clockwise. The imagery shows that these are thin, cirrus clouds characteristic of the storm outflow.

MISR observes the daylit Earth continuously, viewing the entire globe between 82 degrees north and 82 degrees south latitude every nine days. The images shown here span 500 miles (800 kilometers) from north to south. They have been derived from MISR data over a portion of Terra orbit 67,531 from blocks 66-71 within World Reference System-2 Path 19.

MISR was built and is managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif., for NASA's Science Mission Directorate, Washington, D.C. The Terra spacecraft is managed by NASA's Goddard Space Flight Center, Greenbelt, Md. The MISR data were obtained from the NASA Langley Research Center Atmospheric Science Data Center in Hampton, Va. JPL is a division of the California Institute of Technology in Pasadena.

No other operational satellite available to forecasters can provide such clear nighttime images, says Kathy Strabala, a meteorologist and assistant scientist at the University of Wisconsin-Madison. She adds that Suomi NPP data is available right away. "Our use of the direct broadcast antenna means that we can acquire the data in real-time as the satellite overpasses our region."

Meteorologists also can use these nighttime images along with observations from other satellites such as the Tropical Rainfall Measuring Mission to help forecast the strength and direction of hurricanes. University of Wisconsin-Madison meteorology professor Scott Lindstrom says, "You get a visible image at high resolution, in the middle of the night, so you can identify some very key features."

Lindstrom says this information is useful in indicating hurricane intensification, the potential for severe weather, heavy rain and turbulence. For example, he says, this image shows a moonlit "anvil," that's the term used for the highest tops of the storm. It also shows what's called "transverse banding" at the edge of the clouds. Lindstrom says that when those details can be viewed, "a forecaster will know immediately where to expect the heaviest rain and potential for aviation turbulence."

Suomi NPP is the result of a partnership between NASA, the National Oceanic and Atmospheric Administration (NOAA) and the Department of Defense. The ground segment for Suomi NPP is provided by NOAA's Joint Polar Satellite System.

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Tropical Storm Isaac continues to bring high winds and heavy rainfall to much of the Gulf Coast. The strength of the storm is reflected in this infrared image from the Atmospheric Infrared Sounder (AIRS) instrument on NASA's Aqua spacecraft. The colors represent the temperatures of the storm's cloud tops, with the highest clouds - and deepest convection - shown in shades of purple and blue.Image credit: NASA/JPL-Caltech
Isaac - once a Category 1 hurricane and now a strong tropical storm with maximum sustained winds of 70 miles per hour (60 knots) - continues to create havoc across the Gulf Coast, from eastern Texas to Florida. While "only" reaching Category 1 on the Saffir-Simpson hurricane wind scale upon landfall on Aug. 28, Isaac is a slow mover, crawling along at only about six miles (10 kilometers) per hour. This slow movement is forecast to continue over the next 24 to 36 hours, bringing a prolonged threat of flooding to the northern Gulf Coast and south-central United States.

As seen in this infrared image from the Atmospheric Infrared Sounder (AIRS) instrument on NASA's Aqua spacecraft, acquired at 2:41 p.m. CDT on Aug. 29, 2012, the large storm is still relatively well organized and is producing strong bands of thunderstorms. The broad area of purple in the image represents cloud-top temperatures colder than minus 63 degrees Fahrenheit (minus 52 degrees Celsius) around the center of the storm's circulation. It is here that Isaac's strongest storms and heaviest rainfall are now occurring.

According to the National Oceanic and Atmospheric Administration's National Hurricane Center, strong bands of thunderstorms continue to develop over water in the storm's eastern semicircle and southwest of the center. These strong rain bands are forecast to spread gradually to the west tonight across coastal southeastern Louisiana and southern Mississippi, including the New Orleans metropolitan area. The storm is expected to weaken to a tropical depression by Thursday night and a post-tropical remnant low-pressure system by Friday.

Hurricane Isaac is continuing to drop heavy rainfall over Louisiana and Mississippi, and NASA's TRMM satellite identified that rainfall as the storm was making landfall.

On Aug. 29, 2012 at 1 p.m. EDT, Isaac was still a hurricane with maximum sustained winds near 75 mph (120 kmh). Isaac was located about 10 miles northwest (15 km) of Houma, Louisiana and moving slowly. It is moving to the northwest near 6 mph (9 km). Isaac continued bringing heavy rainfall to southeastern Louisiana and southern Mississippi. The threat for dangerous coastal storm surge and inland flooding are expected to continue overnight.

The Tropical Rainfall Measuring Mission (TRMM) satellite flew over Hurricane Isaac twice on the night that Isaac made landfall in Louisiana and headed for New Orleans. TRMM is a joint mission managed by both NASA and JAXA, the Japanese Space Agency.

In the first of the two overflights, the TRMM radar saw two hot towers in the eyewall of Hurricane Isaac just hours before landfall. While hot towers were shooting up in the eyewall over the ocean, Isaac's inner rainband was already lashing Louisiana with heavy rain. Hot towers are common in intensifying tropical cyclones are are a sign that energy is being pumped into the hurricane from the ocean's surface. A "hot tower" is a tall cumulonimbus cloud that reaches at least to the top of the troposphere, the lowest layer of the atmosphere. It extends approximately nine miles (14.5 km) high in the tropics.

Two images were created by Owen Kelley, of NASA's Goddard Space Flight Center, Greenbelt, Md. The background of the first image showed TRMM infrared observations that give a sense of the height of the cloud cover the hides the heavy precipitation inside of of the hurricane. The blue-gray 3D volume contains the light precipitation inside the hurricane, using a 20 dBZ radar-reflectivity threshold.

In the image, an insert reveals details at the center of the hurricane. Two hot towers are indicated by the yellow and orange colors. They are locations where strong updrafts are lifting frozen precipitation above a 14.5 km (9.1 mile) threshold. Water that condenses in updrafts will soon freeze if updrafts lift it above the zero-degree isotherm near 5 kilometers (3.1 miles) altitude. The freezing releases another boost of latent heat, the fuel of hurricanes, following the initial release of latent heat when the water vapor condenses into liquid.

The TRMM radar happened to overfly Hurricane Isaac again just five hours later, shortly after the eyewall made landfall. Robbed of its oceanic source of energy, the eyewall hot towers are gone in this later overflight. Instead of reaching 14.5 km (9.1 mile) altitude, the eyewall merely reaches a 10 km (6.2 mile) altitude, which is indicated by the light green shading at the top of the blue-green volume of light precipitation.

Unfortunately for New Orleans and surrounding areas, TRMM sees that Hurricane Isaac's eyewall was remarkably well organized at that time, despite having made landfall. The insert shows a ring of very intense radar echos in red, echos that exceed 40 dBZ radar reflectivity. The northwest quadrant of his ring of heavy precipitation is almost on top of New Orleans at the time of observation.

An animation of satellite observations from August 27-29, 2012, shows Hurricane Isaac move through the Gulf of Mexico and make its first landfall in southeastern Louisiana on Aug. 28 at 7:45 p.m. EDT (1145 UTC), second landfall on Aug. 29 at 6 a.m. EDT (1000 UTC). This visualization was created by the NASA GOES Project at NASA Goddard Space Flight Center, Greenbelt, Md., using observations from NOAA's GOES-13 satellite.
Credit: NASA/NOAA GOES Project› Download video (21 MB mp4)

NASA and NOAA satellites continue to provide detailed information to forecasters at the National Hurricane Center. Hurricane Isaac's first landfall occurred at 7:45 p.m. EDT in extreme southeastern Louisiana, bringing strong winds and dangerous storm surge along the northern Gulf coast. Landfall occurred in Plaquemines Parish, southwest of the mouth of the Mississippi River. Isaac was a category 1 storm upon landfall with maximum sustained winds of 80 mph (130 kmh).

NASA's Tropical Rainfall Measuring Mission (TRMM) satellite captured a view of Isaac's rainfall rates on Aug. 28 at 11:05 p.m. EDT, just 3 hours and 20 minutes after its first landfall in southeastern Louisiana. The heaviest rainfall rates, near 50 mm (2.0 inches) per hour surrounded the center of the storm, causing inland flooding on its slow crawl.

At 6 a.m. EDT on Aug. 29, Isaac made a second landfall along the southern coast of Louisiana. At that time it was located near latitude 29.3 north and longitude 90.6 west, 35 miles south-southeast of Houma Louisiana, and moving west-northwest at 6 mph (9 kmh).

By 7 a.m. EDT, Isaac's maximum sustained winds were still hurricane strength, at 80 mph (130 kmh) as it continues to feed from the warm waters of the Gulf of Mexico. It was located about 20 miles (30 km) southeast of Houma, La. Near 29.4 north and 90.5 west. Isaac was moving to the northwest at 6 mph (9 kmh) with a minimum central pressure of 970 millibars.

A hurricane warning is in effect for east Of Morgan City, Louisiana to the Mississippi-Alabama border, including metropolitan New Orleans, Lake Pontchartrain and Lake Maurepas. A hurricane watch is in effect for Intracoastal city to Morgan City, Louisiana. A tropical storm warning is in effect for the Mississippi-Alabama Border to Destin, Florida, and from Morgan City to Sabine Pass, Texas. A tropical storm watch is in effect from east of High Island Texas to just west of Sabine Pass.

Flooding is a big threat from Isaac because of its slow movement, and because it is drawing a lot of energy from the warm waters of the Gulf of Mexico. Isolated tornadoes are also possible as Isaac continues moving inland.

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Color-enhanced image of sea surface heights in the Gulf of Mexico, showing Hurricane Isaac’s path through the Gulf and around its warmest waters.Credit: LSU Earth Scan Laboratory/U. of Colorado CCAR/NASA-JPL/Caltech
Seven years after the powerful Category 3 Hurricane Katrina caused widespread devastation along the Gulf Coast, a Category 1 Hurricane Isaac, with maximum sustained winds of 80 miles per hour (70 knots), is making landfall today in southeast Louisiana. And one of the reasons why Isaac is not Katrina is the path it took across the Gulf of Mexico and the temperature of the ocean below, which helps to fuel hurricanes.

In 2005, Hurricane Katrina's maximum wind speeds increased dramatically as the storm passed over a warm ocean circulation feature called the Loop Current that is part of the Gulf Stream. The storm evolved quickly from a Category 3 to a Category 5 event on the Saffir-Simpson Hurricane Wind Scale in a matter of nine hours as it drew heat from the Loop Current. It subsequently dropped in intensity to a Category 3 storm at landfall.

Because the Loop Current and its eddies are warmer, and thus higher in surface elevation, than the surrounding waters, they are easily spotted by satellite altimeter instruments, such as those aboard the NASA/French Space Agency Jason 1 and Ocean Surface Topography Mission/Jason 2 satellites. Scientists use the latest satellite measurements of sea-surface height from these and other satellite altimeters to create maps showing the location, direction and speed of currents in the Gulf of Mexico.

This color-enhanced image of sea surface heights in the northeastern Gulf, produced using data from available satellite altimeters, including NASA's Jason-1 and Jason-2 satellites, shows Isaac's path through the Gulf. The storm skirted around the Loop Current, then caught the outer edge of a warm eddy before passing directly over a cold eddy. The storm's track away from the Gulf's warmest waters has helped to keep Isaac from intensifying rapidly, as Hurricanes Katrina and Rita did in 2005.

Warm eddies have high heat content and great potential to intensify hurricanes, whereas cold eddies have low heat content and may even cause hurricanes to weaken, as was the case with Hurricane Ivan in 2004.

NASA and NOAA satellites continue to provide detailed information on Hurricane Isaac as the storm bears down on the U.S. Gulf coast. NASA's TRMM and Terra satellites captured imagery, and NOAA's GOES-13 satellite provided animations of Isaac's march toward the coast today, Aug. 28.

This is an animation of GOES-13 satellite imagery from Aug. 26-28, 2012 of Hurricane Isaac's track through the Gulf of Mexico. Isaac is headed for New Orleans, exactly 7 years after hurricane Katrina. Credit: NASA/NOAA GOES Project

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The MODIS instrument on NASA's Terra satellite captured a visible image of Hurricane Isaac as it approached Louisiana on Aug. 28 at 12:30 p.m. EDT. A large band of showers and thunderstorms stretched from the Carolinas, west over Georgia, Alabama, Mississippi, Florida and into Louisiana, wrapping into Isaac's center of circulation when it was centered about 100 miles south of the mouth of the Mississippi River.Credit: NASA Goddard MODIS Rapid Response Team
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TRMM captured this image of Isaac as it was approaching the northern Gulf coast at 4:01 UTC, August 28 (12:01 EDT). TRMM shows a broad area of moderate (shown in green) to heavy rain (shown in red) wrapping around the southwestern side of the storm with only moderate to light rain (shown in blue) on the opposite side and no heavy rain near the center. The cloud shield (shown in white) is also well pronounced in the southwestern half of Isaac but inhibited along the northern edge. At the time of this image Isaac was a strong tropical storm with sustained winds of 60 knots (~70 mph).Credit: NASA/SSAI, Hal Pierce
Residents along the northern Gulf coast are bracing for the arrival of Isaac, which was recently upgraded to a hurricane by the National Hurricane Center as of 1:00 p.m. CDT. At that time, the center of Isaac was located about 55 miles (~85 km) south-southeast of the Mississippi and was moving northwest at 10 mph and was nearing southeastern coast of Louisiana.

After crossing the southwestern tip of Haiti during the early morning hours of the 25th of August, Isaac paralleled the northern coast of Cuba the following day and moved through the Florida Straits with the center passing about 40 miles (~65 km) south of Key West, Florida on the afternoon of the 26th. All the while, Isaac remained a tropical storm despite passing over warm water. As it entered the southeastern Gulf of Mexico on the afternoon of August 26th, Isaac seemed poised to intensify with plenty of over warm Gulf water ahead and relatively low wind shear. However, even as Isaac moved northwest through this favorable environment into the central Gulf of Mexico, it was slow to intensify, becoming a stronger tropical storm but not a hurricane until just before landfall. Several factors seemed to inhibit Isaac's intensification. Being a large storm, Isaac's wind field is spread over a large area, making it less responsive to changes in central pressure. Also, dry air intrusions hindered the development of an inner core. The lack of an inner core was the main reason Isaac failed to really intensify.

TRMM captured an image of Isaac on August 28 at 4:01 UTC (12:01 a.m. EDT) as it was approaching the northern Gulf coast. The image was TRMM shows a broad area of moderate (shown in green) to heavy rain (shown in red) wrapping around the southwestern side of the storm with only moderate to light rain (shown in blue) on the opposite side and no heavy rain near the center. The cloud shield (shown in white) is also well pronounced in the southwestern half of Isaac but inhibited along the northern edge. At the time of this image Isaac was a strong tropical storm with sustained winds of 60 knots (~70 mph). Because of its large size, Isaac stills poses a threat for storm surge and it's expected slower movement over Louisiana brings the risk of flooding.

An animation of NOAA's GOES-13 satellite imagery from Aug. 26-28, 2012 of Hurricane Isaac's track through the Gulf of Mexico was animated by NASA's GOES Project at the NASA Goddard Space Flight Center in Greenbelt, Md. The animation shows Isaac is headed for New Orleans, exactly 7 years after hurricane Katrina.

The Moderate Resolution Imaging Spectroradiometer (MODIS) instrument on NASA's Terra satellite captured a visible image of Hurricane Isaac as it approached Louisiana on Aug. 28 at 12:30 p.m. EDT. A large band of showers and thunderstorms stretched from the Carolinas, west over Georgia, Alabama, Mississippi, Florida and into Louisiana, wrapping into Isaac's center of circulation when it was centered about 100 miles south of the mouth of the Mississippi River.

On Aug. 28 at 2 p.m. EDT, Hurricane Isaac's maximum sustained winds were near 75 mph (120 kmh). Isaac is a category one hurricane on the Saffir-Simpson scale. It was centered about 55 miles (85 km) south-southeast of the mouth of the Mississippi River near latitude 28.4 north and longitude 88.7 west. Isaac is moving toward the northwest near 10 mph (17 kmh). The National Hurricane Center expects Hurricane Isaac should reach the coastline of southeastern Louisiana as early as this evening.

At 2 p.m. EDT, the National Hurricane Center noted that tropical-storm-force winds were occurring at the mouth of the Mississippi river. That's where a NOAA observing site located at Southwest Pass, Louisiana reported sustained winds of 60 mph (93 kmh) and a gust to 76 mph (122 kmh) at an elevation of 80 feet.
For full warnings, watches and locations, visit the National Hurricane Center's website at: www.nhc.noaa.gov. For storm history and NASA satellite images and animations, go to: NASA's Hurricane page.

Isaac Becomes a Hurricane in the Gulf of Mexico on Aug. 28 at 11:20 a.m.
This visible image of Hurricane Isaac taken at 12:40 p.m. EDT on Aug. 28 from NOAA's GOES-13 satellite shows the huge extent of the storm, where the eastern-most clouds lie over the Carolinas and the western-most clouds are brushing east Texas. Isaac became a Category 1 hurricane on Aug. 28 at 11:20 a.m. EDT with maximum sustained winds near 75 mph (120 kmh). It was located about 75 miles (115 km) south-southeast of the mouth of the Mississippi River, near28.1 North and 88.6 West. Isaac was moving to the northwest near 10 mph (17 kmh). Outer bands of thunderstorms have already moved over Louisiana, Alabama, Mississippi and Georgia. Credit: NASA GOES Project› Larger image

An animation of satellite observations from August 26-28, 2012 shows Tropical Storm Isaac moving past the Florida Keys and into the Gulf of Mexico, nearing landfall in the U.S. Gulf states. This visualization was created by the NASA GOES Project at NASA Goddard Space Flight Center, Greenbelt, Md., using observations from NOAA's GOES-13 satellite. Credit: NASA/NOAA GOES Project

NASA satellites have been providing valuable data to forecasters at the National Hurricane Center watching the development and progression of powerful Tropical Storm Isaac as it heads for landfall.

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The MODIS instrument on NASA's Aqua satellite captured this visible image of Tropical Storm Isaac on Aug. 27 at 3:00 p.m. EDT is it was moving northwest through the Gulf of Mexico. Isaac's large reach is seen by its eastern cloud cover over the entire state of Florida.Credit: NASA Goddard MODIS Rapid Response Team
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This visible image of Tropical Storm Isaac taken from NOAA's GOES-13 satellite shows the huge extent of the storm, where the eastern-most clouds lie over the Carolinas and the western-most clouds are brushing east Texas. The image was captured on Aug. 28 at 8:40 a.m. EDT.Credit: NASA GOES Project
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On Aug. 27 at 3:00 p.m. EDT the AIRS instrument on Aqua captured infrared data on Isaac's clouds. Cloud top temperatures were colder (purple) than –63F (-52C) around the center of circulation and the western quadrant of the storm, and in a large band of thunderstorms east of the center of circulation, over Florida. That's where the strongest storms and heaviest rainfall was occurring.Credit: NASA JPL, Ed Olsen
The Moderate Resolution Imaging Spectroradiometer (MODIS) instrument on NASA's Aqua satellite captured this visible image of Tropical Storm Isaac on Aug. 27 at 3:00 p.m. EDT is it was moving northwest through the Gulf of Mexico. Isaac's large reach is seen by its eastern cloud cover over the entire state of Florida. At the same time, the Atmospheric Infrared Sounder (AIRS) instrument on Aqua captured infrared data on Isaac's clouds. Cloud top temperatures were colder than –63F (-52C) around the center of circulation and the western quadrant of the storm, and in a large band of thunderstorms east of the center of circulation, over Florida and parts of Cuba. That's where the strongest storms and heaviest rainfall was occurring.

On Aug. 28 at 8:40 a.m. EDT, a visible image of Tropical Storm Isaac taken from NOAA's GOES-13 satellite showed the huge extent of the storm, where the eastern-most clouds lie over the Carolinas and the western-most clouds are brushing east Texas. The image was created by the NASA GOES Project at the NASA Goddard Space Flight Center in Greenbelt, Md. Tropical-storm-force winds extend outward up to 205 miles (335 km) from the center of circulation, making the storm about 410 miles in diameter.

Warnings and watches in effect on Tuesday, Aug. 28, 2012 are many. A hurricane warning is in effect for east of Morgan City Louisiana to the Alabama-Florida Border, including Metropolitan New Orleans, Lake Pontchartrain, and Lake Maurepas. A hurricane watch is in effect for Intracoastal City to Morgan City, Louisiana. Tropical Storm Warnings are in effect from the Alabama-Florida border to the Aucilla River, and Morgan City to Cameron, Louisiana. A Tropical Storm Watch is in effect from east of High Island, Texas to just west of Cameron, Louisiana.

On Aug. 28 at 8 a.m. EDT, Tropical Storm Isaac's maximum sustained winds were just under hurricane force, at 70 mph (110 kmh). The center of Tropical Storm Isaac was located near latitude 27.8 north and longitude 88.2 west, only about 105 miles (170 km) south-southeast of the mouth of the Mississippi River. Isaac is moving northwest at 7 mph (11 kmh) and is expected to continue in that direction for the next day or two, but it's speed is expected to fluctuate. The National Hurricane Center noted that the center of Isaac will be near or over the Louisiana coast tonight, Aug. 28, or early on Aug. 29.

Storm surge is a deadly part of any landfalling tropical cyclone. The National Hurricane Center (NHC) is warning that storm surge will be highest from Isaac from southeastern Louisiana to Mississippi, where surge levels are expected between 6 and 12 feet during times of high tide. Alabama's coast may experience surge between 4 and 8 feet, while south-central Louisiana and the Florida panhandle can expect between 3 and 6 feet. Florida's west coast including Apalachee Bay can expect a storm surge between 1 and 3 feet.

The NHC expects hurricane conditions in the northern Gulf Coast warning area during the afternoon of Aug. 28. As conditions worsen, isolated tornadoes are possible as with any landfalling tropical cyclone.

NASA's Tropical Rainfall Measuring Mission (TRMM) satellite has seen large rainfall rates within Tropical Storm Isaac, and those large rainfall rates and slow movement of the storm will lead to high rainfall totals. The National Hurricane Center expects 7 to 14 inches of rain with possible isolated maximum amounts of 20 inches in southeastern Louisiana, southern Mississippi, southern Alabama and the extreme western Florida Panhandle.

For updates on location from the National Hurricane Center, visit: www.nhc.noaa.gov

An animation of satellite observations from August 25-27, 2012, shows Tropical Storm Isaac moving past Cuba and the Florida Keys and into the eastern Gulf of Mexico. This visualization was created by the NASA GOES Project at NASA Goddard Space Flight Center, Greenbelt, Md., using observations from NOAA's GOES-13 satellite.
Credit: NASA/NOAA GOES Project› Download video (21 MB mp4)

NASA's Atmospheric Infrared Sounder or AIRS instrument is an infrared "eye" that flies onboard NASA's Aqua satellite. AIRS has been providing the National Hurricane Center with valuable temperature data on Isaac's clouds and the surrounding sea surface temperatures, and a time series of data shows that Isaac is consolidating.

The AIRS instrument has been monitoring Tropical Storm Isaac for several days. AIRS data from Aug. 24, 25, 26 and 27 showed Isaac's movements through the eastern and central Caribbean Sea, across eastern Cuba and into the Gulf of Mexico. On Aug. 24, Isaac's strongest convection (rising air that forms the thunderstorms that make up a tropical cyclone) appeared all around the center, except in the western quadrant of the storm. On Aug. 25, when Isaac was affecting Haiti, it appeared more disorganized, and the strongest storms extended from southwestern Haiti into the central Caribbean Sea. On Aug. 26, AIRS data showed the area of strong convection had increased and the largest area was over the Florida Keys, with bands of strong thunderstorms extending over southeastern Florida and the Bahamas. On Aug. 27, Isaac's center of circulation appeared more rounded on AIRS imagery, indicating the circulation center was becoming more organized.

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NASA's Aqua satellite passed over Tropical Storm Isaac on Aug. 26 at 18:15 UTC (2:15 p.m. EDT) when it was over Florida and Cuba and the MODIS instrument captured this visible image of the storm.Credit: NASA Goddard MODIS Rapid Response Team
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The AIRS instrument onboard NASA's Aqua satellite has been monitoring Tropical Storm Isaac for several days. Shown here are AIRS data from Aug. 24 and 25 (top left and right) and Aug. 26 and 27 (bottom left and right). AIRS has been providing infrared data about cloud temperatures, and sea surface temperatures around the storm.Credit: NASA JPL, Ed Olsen
Southeasterly wind shear and the larger than average wind radii, and entrance of some dry air had been keeping Isaac from strengthening more quickly today, Aug. 27. That wind shear is the result of an upper-level low pressure area that lies southwest of Tropical Storm Isaac. As that low moves away and the wind shear lessens, Isaac will have more ability to strengthen.

Where is Isaac on Aug. 27?

At 11 a.m. EDT (1200 UTC) on Monday, Aug. 27, Isaac was a strong tropical storm with maximum sustained winds near 65 mph (100 kmh). Isaac is expected to become a hurricane in the next day or two over the warm waters of the Gulf of Mexico. When Isaac reaches maximum sustained winds of 74 mph, it will be classified as a category one hurricane. Isaac's cloud extent is about 480 miles in diameter, as tropical-storm-force winds extend outward up to 240 miles (390 km) from the center.

Tropical Storm Isaac was located about 250 miles (400 km) south of Apalachicola, Fla. and about 310 miles (500 km) southeast of the mouth of the Mississippi River. That puts Isaac's center near latitude 25.7 north and longitude 84.7 west. Isaac is moving toward the west-northwest near 14 mph (22 kmh) and the tropical storm is expected to continue on that track, but slow down before turning to the northwest on Tuesday, Aug. 28. The National Hurricane Center expects Isaac to move over the eastern Gulf of Mexico later today, Aug. 27 and approach the northern Gulf coast in the hurricane warning area on Tuesday, Aug. 28.

Hurricane Warnings and Watches

A Hurricane Warning is in effect from east of Morgan City, Louisiana to Destin, Fla., including metropolitan New Orleans, Lake Pontchartrain and Lake Maurepas. A Hurricane Watch is in effect for Intracoastal City to Morgan City, Louisiana.

Tropical Storm Warnings and Watches

A Tropical Storm Warning is in effect for the Florida Peninsula from Ocean Reef Southward on the east coast and from Tarpon Springs southward on the west coast; the Florida Keys including the Dry Tortugas and Florida Bay; east of Destin, Fla. to the Suwannee River; and Intracoastal City to Morgan City, Louisiana. A Tropical Storm Watch is in effect for east of Sabine Pass to west of Intracoastal City, La.

Heavy rainfall, gusty winds, isolated tornadoes and dangerous surf can be expected along Isaac's path. For updates on local effects, go the National Hurricane Center website.

Tropical Storm Isaac has been raining on southern Florida and the Bahamas while still centered over Cuba, and NASA's TRMM satellite captured data on the rate in which rain has been falling from the storm. Isaac is expected to intensify into a hurricane as it moves northward, parallel to Florida's west coast over the next couple of days.

The Tropical Rainfall Measuring Mission satellite known as TRMM had a fair quality pass above the northern part of tropical storm Isaac on Sunday August 26, 2012 at 0417 UTC (12:17 a.m. EDT). Rainfall derived from TRMM's Microwave Imager (TMI) showed that Isaac was disorganized but was producing rainfall from the Bahamas through the Florida Keys. A band of rain from Isaac was also seen over Key West, Florida. Isaac is expected to be over the Florida Keys today, Aug. 26, 2012.

Isaac Expected To Become a Hurricane Today, Aug. 26

On Sunday. Aug. 26 at 8 a.m. EDT (1200 UTC) Tropical Storm Isaac was just below hurricane strength (which is 74 mph sustained winds). Isaac's maximum sustained winds were near 65 mph (100 kmh) and Isaac is expected to become a hurricane by the time it reaches the Florida Keys.

The center of tropical storm Isaac was located near latitude 23.5 north and longitude 80.0 west. According to the National Hurricane Center, Isaac is moving toward the west-northwest near 20 mph (31 kmh). A west-northwestward to northwestward motion is expected during the next 48 hours with a gradual decrease in forward speed.

Isaac is a large storm, as tropical-storm-force winds extend 205 miles from the center, making it about 410 miles in diameter. The cloud cover from Isaac is larger than that. The distance from Key West to Jacksonville, Fla. is 506 miles, and Isaac's clouds drape over that entire area and more, as its center still sits just north of eastern Cuba. Even if Isaac's center remains west of the Florida coast while it tracks north, Isaac's clouds, winds and rains will extend over the state.

Isaac's Wide Reach Seen on Satellite

A visible image of Tropical Storm Isaac was captured by NOAA's GOES-13 satellite on Sunday, Aug. 26 at 9:45 a.m. EDT. The visible image was created by the NASA GOES Project at the NASA Goddard Space Flight Center, Greenbelt, Md. and showed Isaac's clouds extending from Cuba to northern Florida.

Large Rainfall Totals Expected

While the TRMM satellite continues to measure rainfall rates, the National Hurricane Center (NHC) is using that data to determine rainfall totals from the storm. The NHC expects total rainfall accumulations of 4 to 8 inches with maximum amounts of 12 inches across the Florida Keys and southern peninsula of Florida. Portions of eastern Cuba may also receive the same amount of rainfall. Meanwhile the central and southern Bahamas can expect between 3 and 6 inches of rainfall. That kind of heavy rainfall leads to inland flooding.

Hurricane Conditions, Tornadoes, Dangerous Surf

In addition to the large rainfall totals, hurricane conditions are expected in the hurricane warning area in southwestern Florida and the Florida Keys today. Isolated tornadoes are always a possibility whenever a tropical cyclone moves over land. In addition, rough seas and rip-tides are expected in the Bahamas, the Turks and Caicos, eastern and central Cuba, the Florida peninsula and the Florida Keys over the next several days as Isaac moves north.

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The TRMM satellite captured rainfall data on August 25, 2012 at 0512 UTC (1:12 AM EDT) when it passed over Tropical Storm Isaac, whose center was close to the southern coastline of Haiti. The TRMM data showed that Isaac was producing Light to moderate rainfall over Haiti. TRMM revealed that the heaviest rain (in red) of over 50mm/hour (~2 inches) was occurring in bands of thunderstorms moving over the Dominican Republic.Credit: SSAI/Hal Pierce
NASA's Tropical Rainfall Measuring Mission (TRMM) has been busy measuring the heavy rainfall from Tropical Storm Isaac when it was over Haiti and the Dominican Republic on Aug. 25. Warnings and Watches are in effect in Hispaniola, Cuba and south Florida as Isaac heads north.

The TRMM satellite captured rainfall data on August 25, 2012 at 0512 UTC (1:12 AM EDT) when it passed over Tropical Storm Isaac, whose center was close to the southern coastline of Haiti. The TRMM data showed that Isaac was producing Light to moderate rainfall over Haiti. TRMM revealed that the heaviest rain of over 50mm/hr (~2 inches) was occurring in bands of thunderstorms moving over the Dominican Republic.

To create the image of rainfall, a rainfall analysis from TRMM's Microwave Imager (TMI) and Precipitation Radar (PR) instruments were overlaid on an enhanced infrared image from TRMM's Visible and InfraRed Scanner (VIRS) instrument at NASA's Goddard Space Flight Center in Greenbelt, Md.

The National Hurricane Center (NHC) expects the heavy rainfall that NASA's TRMM satellite identified to fall over Hispaniola. In the NHC advisory on Aug. 25 at 8 a.m., the NHC expects "total rainfall accumulations of 8 to 12 inches...with maximum amounts of 20 inches...are possible over Hispaniola. These rains could cause life-threatening flash floods and mudslides.

Total rain accumulations of 4 to 8 inches...with maximum amounts of 12 inches...are possible across Jamaica...the central and eastern portions of Cuba...the Florida Keys and the southern peninsula of Florida. Total rain accumulations of 2 to 4 inches are possible over the central and southeastern Bahamas."

At 8 a.m. EDT (1200 UTC) on Saturday, Aug. 25, Tropical Storm Isaac's maximum sustained winds were near 60 mph (95 kmh). It was located about 95 miles (150 km) east-southeast of Guantanamo, Cuba, near 19.7 North and 73.8 West. Isaac was moving into the Windward Passage, which is a strait located between eastern Cuba and Haiti. Isaac was moving to the northwest at 14 mph (22 kmh) and had a minimum central pressure of 998 milibars.

The warnings and watches are numerous. A hurricane warning is in effect for the Florida
Keys including the Dry Tortugas, and the west coast of Florida from Bonita Beach southward to Florida Bay. A hurricane watch is in effect for Haiti, the Florida east coast from Golden Beach southward, and Andros Island in the Bahamas.

A tropical storm warning is in effect for the Dominican Republic, Haiti, and Cuban provinces of Ciego De Avila, Sancti Spiritus, Villa Clara, Camaguey, Las Tunas, Granma, Holguin, santiago de Cuba, and Guantanamo. A tropical storm watch is also in effect for the Bahamas, Turks and Caicos islands, and the Florida east coast from Jupiter Inlet south and Lake Okeechobee.

A tropical storm watch is in effect for the Cuban provinces of Matanzas and Cienfuegos, Jamaica and the Florida east coast north of Jupiter Inlet to Sebastian Inlet.

Hurricane conditions are expected in the hurricane warning area in southwest Florida and the Florida Keys on Sunday. Storm surge is expected to be largest in southwestern Florida, where the NHC expects a surge between 5 and 7 feet. The southeastern Florida coast, the Florida Keys, Hispaniola and Cuba are expected to see a surge between 1 and 3 feet.

The National Hurricane Center forecasts some strengthening later today, and expects Isaac to become a hurricane on Sunday, Aug. 26.

NASA's Terra satellite passed over Tropical Storm Isaac on Aug. 24 at 15:20 UTC (11:20 a.m. EDT) as it continued moving through the eastern Caribbean Sea. The MODIS instrument onboard Aqua captured a visible image of the storm filling up the eastern Caribbean.

NASA's Tropical Rainfall Measuring Mission (TRMM) satellite flew above tropical storm Isaac on Aug. 24 2:13 a.m. EDT and revealed heavy rainfall around Isaac's center. Rainfall rates were over 90mm/hr (~3.54 inches) within several strong convective storms. TRMM Precipitation Radar data were used to make a 3-D view of Isaac's structure that showed some storms near Isaac's center were reaching heights of about 16km (~9.94 miles). These towers contain Isaac's heaviest rains and act to energize the core of the storm.

The Atmospheric Infrared Sounder (AIRS) instrument onboard NASA's Aqua satellite captured an infrared image of the eastern edge of Tropical Storm Isaac on Aug. 24 at 1:52 a.m. EDT. The AIRS image measures cloud top temperatures, and revealed strong thunderstorms with cloud-top temperatures as cold as -63F (-52C) around the center of circulation and in a large band of thunderstorms east of the center of circulation.

At 2 p.m. EDT on Aug. 24, Isaac's maximum sustained winds were near 60 mph (95 kmh). The National Hurricane Center noted that Isaac could strengthen later before reaching the coast of Hispaniola tonight, Aug. 24. Hispaniola is an island that contains the Dominican Republic and Haiti. Isaac is located about 135 miles (215 km) south-southeast of Port au Prince, Haiti, near latitude 16.8 north and longitude 71.4 west. Isaac is now moving toward the northwest near 14 mph (22 kmh).

Isaac is expected to reach hurricane status over the weekend of Aug. 25-26 and NASA satellites will continue providing valuable temperature, rainfall, visible and infrared data.

NASA's Tropical Rainfall Measuring Mission satellite, known as TRMM, has been monitoring the rainfall rates within Tropical Storm Isaac as the storm entered the eastern Caribbean Sea.

After becoming a tropical storm in the central Atlantic on August 21, Isaac continued tracking westward and entered the eastern Caribbean early on the evening of Aug. 22 with the ill-defined center passing just south of Guadeloupe in the Leeward Islands. Since becoming a tropical storm, Isaac has shown little change in intensity, but the National Hurricane Center expects that to change over the weekend of Aug. 25-26, 2012.

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On Aug. 23, 2012 as 1:40 p.m. EDT NASA's Aqua Satellite flew over Tropical Storm Isaac the MODIS instrument captured this visible image of the storm as it continues moving through the eastern Caribbean Sea.
Credit: NASA Goddard MODIS Rapid Response Team
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NASA's TRMM satellite saw Isaac just after it passed the Leeward Islands and entered the eastern Caribbean. This image was taken at 5:20 p.m. EDT on Aug. 22, 2012. Although there are areas of moderate (shown in green) to heavy rain (shown in red), these are mainly located southwest of the overall center.Credit: SSAI/NASA, Hal PierceNASA's TRMM Satellite Sees Heavy Rainfall

NASA's TRMM satellite saw Isaac just after the storm passed the Leeward Islands and entered the eastern Caribbean. TRMM captured an image of Isaac's rainfall at 21:20 UTC (5:20 p.m. EDT) August 22, 2012. Although there were areas of moderate to heavy rain, they were mainly located southwest of the overall center. Isaac still showed no sign of an eye with very little rain near the overall center, which was located near 16 North latitude and 61.2 West longitude. There was also not much banding (curvature) in the rain features. Overall, those characteristics indicated that Isaac is still not well organized. At the time TRMM passed over Isaac, it was still a weak tropical storm with sustained winds estimated at 40 knots (~46 mph) and was moving due west at 22 mph (35.4 kmh). TRMM is a joint mission between NASA and the Japanese space agency JAXA.

NASA's Aqua Satellite Sees Isaac's Large Reach

On Aug. 23, 2012 as 1:40 p.m. EDT NASA's Aqua Satellite flew over Tropical Storm Isaac the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument captured a visible image of the storm as it continued moving through the eastern Caribbean Sea. The visible image showed the large extent of Tropical Storm Isaac. Isaac's tropical storm-force winds extend 185 miles (297.7 km) from the center, making the storm about 370 miles (595.5. km) in diameter. For a high resolution image, please visit the MODIS Rapid Response website.

Watches and Warnings

On Aug. 24, NOAA's National Hurricane Center (NHC) many watches and warnings were in effect as Isaac continued to slowly build up steam. A Hurricane Watch is in effect for Haiti. A Tropical Storm Warning is in effect for Dominican Republic, Haiti, and the Cuban Provinces of Camaguey, Las Tunas, Granma, Holguin, Santiago De Cuba, and Guantanamo. The Tropical Storm Warning is also in effect for the southeastern Bahamas including the Acklins, Crooked Island, Long Cay, the Inaguas, Mayaguana, and the Ragged Islands, and the Turks and Caicos Islands.

A Tropical Storm Watch is in effect for the Cuban Provinces of Ciego De Avila, Sancti Spiritus, and Villa
Clara, Andros Island and the Central Bahamas including Cat Island, the Exumas, Long Island, Rum Cay, San Salvador and Jamaica.

On Aug. 24 at 8 a.m. EDT (1200 UTC) Tropical Storm Isaac's maximum sustained winds were near 50 mph (80
Kmh) with higher gusts. Additional strengthening is forecast while Isaac's center remains over water, according to NHC forecasters. Isaac was about 175 miles (280 km) south-southwest of Santo Domingo, Dominican Republic, and about 220 miles (355 km) southeast of Port au Prince, Haiti. That puts Isaac's center near latitude 16.0 north and longitude 70.3 west. Isaac is moving toward the west near 15 mph (24 kmh) and the NHC expects Isaac to turn west-northwest, then north. According to NHC forecasters, Isaac's center will move near or over Hispaniola today, Aug. 24 and near or over southeastern Cuba on Saturday, Aug. 25.

The heavy rainfall that the TRMM satellite observed is expected to be problematic for Hispaniola and Cuba. The NHC expects extreme rainfall totals of between 8 and 12 inches, with isolated amounts to 20 inches. The potential for flash-flooding and mudslides is present. Eastern Cuba and Jamaica may receive between 4 and 8 inches with isolated totals of 12 inches, while Puerto Rico and the Virgin Islands may get between 2 and 4 inches of rainfall, with isolated totals to 6 inches. Tropical storm-force winds, heavy surf and storm surges are also expected in those areas as Isaac continues on its track. For a full forecast, go to NHC's web page.

After a quiet July, the Atlantic has seen a sharp increase in tropical activity. With the heart of the hurricane season now here, two tropical systems are currently making their way through the Atlantic, Tropical Storm Isaac and TD10 (the 10th tropical depression of the season). During the peak of the season, more storms form further out in the central Atlantic from tropical waves, known as African easterly waves, that move off of the coast of Africa and make their way westward across the tropical Atlantic. These disturbances are often the precursors for tropical storms and hurricanes. The last six storms that formed, including Isaac and TD 10, all formed in August, all originated as African easterly waves, and all formed out over the central tropical Atlantic.

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This visible image of Tropical Storm Isaac was captured by NOAA's GOES-13 satellite on Aug. 23 at 7:45 a.m. EDT as it was lashing the eastern Caribbean.Credit: NASA/NOAA GOES Project
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NASA's TRMM satellite captured rainfall rates in Tropical Storm Isaac on Aug. 22. The image shows a top-down view of the rain intensities. There is some evidence of weak banding (curvature) in the western half of the storm as depicted by the loose arc shape to the rain bands (blue areas, indicating light rain) there. Rain intensities in and around the center are light to moderate with no evidence of an eye. Areas of more intense rain (shown in red) are located away from the center to the southeast.Credit: SSAI/NASA, Hal Pierce
Isaac formed from a tropical wave that moved off of the coast of Africa on Aug. 17. Four days later on the morning of Aug. 21, the wave had intensified and developed enough of a circulation to become a tropical depression, TD 9. Later that same day, the National Hurricane Center (NHC) upgraded the system to Tropical Storm Isaac with sustained winds reported at 35 knots (~40 mph). Isaac then continued to track westward through the central Atlantic towards the Lesser Antilles.

The Tropical Rainfall Measuring Mission (or TRMM) satellite captured an image of Isaac as it was nearing the Lesser Antilles early on the morning of Aug. 22. The image was taken at 06:29 UTC (2:29 a.m. EDT) on Aug. 22, 2012. TRMM is a joint mission between NASA and the Japanese space agency JAXA.

TRMM data was used to create an image showing a top-down view of the rain intensities within Isaac. Images are created by the NASA TRMM team, located at the NASA Goddard Space Flight Center in Greenbelt, Md. Rain rates in the center of the swath were created from the TRMM Precipitation Radar (PR), while those in the outer swath were created using the TRMM Microwave Imager (TMI). The TRMM team then overlaid the rain rates on enhanced infrared (IR) data from the TRMM Visible Infrared Scanner (VIRS).

Once the data was combined to form one image, TRMM revealed that Isaac was still in its formative stage. There was some evidence of weak banding (curvature) in the western half of the storm as depicted by a loose arc shape to the rain bands (indicating light rain) there. Rain intensities in and around the center were light to moderate with no evidence of an eye. Areas of more intense rain were located away from the center to the southeast. Overall, the imagery indicated Isaac still had a fairly weak circulation. At the time of the image, Isaac was a weak tropical storm with sustained winds still estimated at 35 knots (40 mph/65 kmh), and the center was located about 300 miles (~380 miles) due east of Guadeloupe. The storm was moving due west at 18 mph.

At 8 a.m. EDT on Thursday, August 23, Isaac's maximum sustained winds were near 40 mph (65 kmh).
Isaac's center was near 15.4 North latitude and 64.8 West longitude, about 225 miles (360 km) south-southeast of San Juan, Puerto Rico, or about 315 miles (505 km) east-southeast of Isla Saona, Dominican Republic. Isaac continues to move west at 13 mph (21 kmh). The National Hurricane Center expects Isaac to continue moving west and "pass through the Lesser Antilles as a tropical storm before entering the eastern Caribbean, where it could
intensify into a hurricane."

A Hurricane Warning is in effect for the south coast of Dominican Republic from Isla Saona westward to the Haiti-Dominican Republic southern border and all of Haiti. A Tropical Storm Warning is in effect for the British Virgin Islands, Puerto Rico, Vieques, Culebra, and the U.S. Virgin Islands, in addition to the north coast of the Dominican Republic from the Haiti-Dominican Republic's northern border eastward to the north of Isla Saona.

A Tropical Storm Watch is in effect for the southeastern Bahamas including the Acklins, Crooked Island, Long Cay, The Inaguas, Mayaguana, and the Ragged Islands and the Turks and Caicos Islands.

An animation of satellite observations from August 19-22, 2012, shows the development and movement of Tropical Storm Isaac toward the Lesser Antilles. This visualization was created by the NASA GOES Project at NASA Goddard Space Flight Center, Greenbelt, Md., using observations from NOAA's GOES-13 satellite.
Credit: NASA/NOAA GOES Project

There are now two active tropical cyclones in the Atlantic and NASA is generating satellite imagery to monitor their march westward. Tropical Storm Isaac is already bringing rainfall to the Lesser Antilles today, Aug. 22, Tropical Depression 10 formed in the eastern Atlantic, and another low fizzled in the western Gulf of Mexico.

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This visible image captured by NOAA's GOES-13 satellite on Aug. 22 at 1445 UTC shows Tropical Storm Isaac over the Lesser Antilles, and newborn Tropical Depression 10 trailing behind in the central Atlantic.Credit: NASA/NOAA GOES Project
› View larger imageThe Atmospheric Infrared Sounder (AIRS) instrument onboard NASA's Aqua satellite captured an infrared image of Tropical Storm Isaac on Aug. 22 at 2:05 a.m. EDT, as it was bringing heavy rainfall to the Lesser Antilles. Strong thunderstorms appeared in a band of thunderstorms in Isaac's western quadrant that had cloud top temperatures as cold as -63F (-52C) (in purple).Credit: NASA JPL, Ed Olsen
Tropical Storm Isaac formed late on Aug. 21 from Tropical Depression 9 and immediately caused warnings and watches. Tropical Depression 10 formed during the morning hours on Aug. 22 in the central Atlantic, east of Isaac and appears to be following the tropical storm on NOAA's GOES-13 satellite imagery. NOAA's GOES-13 satellite captured an image of Tropical Storm Isaac over the Lesser Antilles, and newborn Tropical Depression 10 trailing behind on Aug. 22 at 1445 UTC (10:45 a.m. EDT). The image was created by the NASA GOES Project at the NASA Goddard Space Flight Center in Greenbelt, Md. Both storms are showing good circulation.

The Atmospheric Infrared Sounder (AIRS) instrument onboard NASA's Aqua satellite captured an infrared image of Tropical Storm Isaac on Aug. 22 at 2:05 a.m. EDT, as it was bringing heavy rainfall to the Lesser Antilles. Strong thunderstorms appeared in a band of thunderstorms in Isaac's western quadrant that had cloud top temperatures as cold as -63F (-52C).

Watches and Warnings in Effect

The National Hurricane Center has posted Warnings and Watches for Tropical Storm Isaac. A Tropical Storm Warning is in effect for Martinique, Dominica, Guadeloupe and the surrounding islands, and St. Martin, St. Kitts, Nevis, Antigua, Barbuda, Montserrat, and Anguilla, Saba, St. Eustatius, and St. Maarten, British Virgin Islands, Puerto Rico, Vieques, Culebra, and the U.S. Virgin Islands.

There are also hurricane and tropical storm watches in effect. A Hurricane Watch is in effect for Puerto Rico, Vieques, Culebra, and the U.S. and British Virgin Islands; the south coast of the Dominican Republic from Isla Saona westward to the Haiti-Domenican Republic southern border. A Tropical Storm Watch is in effect for the north coast of the Dominican Republic from the Haiti-Dominican Republic northern border eastward to north of Isla Saona.

At 11 a.m. EDT (1500 UTC) on Aug. 22, Tropical Storm Isaac had maximum sustained winds near 45 mph (75 kmh), and the NHC said that strengthening is forecast. Isaac could become a hurricane by Thursday or Thursday night, Aug. 23. The center of Isaac was about 140 miles (230 km) east of Guadaloupe, near latitude 15.9 north and longitude 59.3 west. Isaac is moving westward near 21 mph (33 kmh) is expected to stay on this track over the next couple of days.

The NHC said, "On the forecast track the center of Isaac should move through the Leeward Islands this evening and pass near or south of the Virgin Islands and Puerto Rico on Thursday (Aug. 23) and approach the Dominican Republic Thursday night and Friday (Aug. 24).

System 95L Fizzles Out

The third low pressure area that forecasters had been watching for possible development has fizzled out, now that it moved inland in northeastern Mexico. The NHC gives it a "near zero percent" chance of development now.

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This NOAA GOES-13 satellite image taken on Aug. 21 at 7:45 a.m. EDT shows three of the four tropical systems being watched in the Atlantic Ocean basin. From left to right are: System 95L, Tropical Depression 9 and System 96L. Post-tropical Storm Gordon is just beyond the horizon.Credit: NASA/NOAA GOES Project
NASA Sees an Active Tropical Atlantic Again

The Atlantic Ocean is kicking into high gear with low pressure areas that have a chance at becoming tropical depressions, storms and hurricanes. Satellite imagery from NASA's Terra and Aqua satellites have provided visible, infrared and microwave data on four low pressure areas. In addition, NASA's GOES Project has been producing imagery of all systems using NOAA's GOES-13 satellite to see post-Tropical Storm Gordon, Tropical Depression 9, and Systems 95L and 96L.

Tropical Storm Gordon is no longer a tropical storm and is fizzling out east of the Azores. Tropical Depression 9 was born on Aug. 20 and continues to get organized. Behind Tropical Depression 9 in the eastern Atlantic is another low pressure area called System 96L. In the Gulf of Mexico lies another low, called System 95L. In an image taken from NOAA's GOES-13 satellite on Aug. 21 at 7:45 a.m. EDT, all of the systems were visible except for post-tropical Storm Gordon. The storms are seen lined up along the Atlantic basin from left to right with System 95L in the Gulf of Mexico, Tropical Depression 9 just east of the Caribbean Sea and System 96L in the eastern Atlantic Ocean.

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On Aug. 20 at 12:35 a.m. EDT before System 94L organized into Tropical Storm 9, NASA's Aqua satellite passed overhead, and the AIRS instrument captured an infrared image of the storm. It showed that the strongest convection (purple) were located south of the center of circulation.Credit: NASA JPL, Ed OlsenTropical Depression 9

On Aug. 20 at 0435 UTC (12:35 a.m. EDT) before System 94L organized into Tropical Storm 9, NASA's Aqua satellite passed overhead, and the Atmospheric Infrared Sounder (AIRS) instrument captured an infrared image of the storm. It showed that the strongest convection (rising air that forms the thunderstorms that make up the tropical cyclone) were located south of the center of circulation. Those thunderstorms had cold cloud top temperatures of -63 Fahrenheit (-52 Celsius) that indicated there was strong uplift in the low pressure area, and were an indication that the system could strengthen, which it did later into a depression.

Tropical Depression 9 has been the cause for tropical storm warning posts in a number of islands. On Aug. 21, a Tropical Storm Warning is in effect for Dominica, Guadeloupe, Desirade, Les Saintes, Marie Galante, and St. Martin.

TD9 appears as a rounded storm on the GOES-13 satellite image from Aug. 21. In the image, low pressure area "System 96L" trails to the southwest of TD9.

On Aug. 21 at 8 a.m. EDT (1200 UTC) Tropical Depression 9 (TD9) had maximum sustained winds near 35 mph (55 kmh) and is expected to strengthen into a tropical storm later today. It was located about 645 miles (1,035 km) east of Guadeloupe near latitude 15.1 north and longitude 51.8 west. TD90 is moving toward the west near 20 mph (32 kmh) and is expected to continue moving in that direction for the next couple of days, according to the National Hurricane Center (NHC).

NHC said that the cyclone should move through the central Lesser Antilles on Wed., Aug. 22 and move into the Caribbean Sea the next day. NHC expects rainfall between 4 and 8 inches to affect the northern Windward and the Leeward Islands, accompanied by heavy surf and rip tides.

System 96L in Eastern Atlantic

System 96L appears well-defined on the GOES-13 satellite imagery. It is associated with a tropical wave, and is spinning about 425 miles southwest of the Cape Verde Islands. The NHC said that System 96L could very well become the tenth tropical depression of the Atlantic Hurricane Season in the next day or two. It is moving to the west at 15 mph.

System 95L Struggles in the Gulf of Mexico

The eastern-most low pressure area in the Atlantic Ocean basin is System 95L, located in the western Gulf of Mexico. It is producing disorganized showers and thunderstorms just off-shore of the northeastern coast of Mexico. The low-level center of circulation is also elongated, which is a bad sign for a tropical cyclone trying to organize. Tropical cyclones need a strong, rounded circulation to strengthen. The NHC noted that slow development is still possible before System 95L moves inland in northeastern Mexico later in the day on Wed. Aug 21. The system has a 30 percent chance of developing before that happens. Once inland, its chances for development are greatly reduced because it will be cut off from its life-giving warm water supply.

Tropical Storm Gordon is History

On Monday, August 20, satellite imagery and surface data revealed that Tropical Storm Gordon lost his tropical characteristics, making it a post-tropical cyclone. According to Reuters news, Gordon caused some power outages, fallen trees and minor flooding.

The National Hurricane Center issued their final advisory on Gordon on August 20 at 5 p.m. EDT (2100 UTC). At that time, Gordon still had maximum sustained winds near 45 mph (75 kmh) and was weakening. Gordon was about 370 miles (595 km) east-northeast of the Azores, near latitude 39.2 north and longitude 20.3 west. Gordon was moving east-northeast near 16 mph (26 kmh) and was expected to turn southeast while weakening further. Gordon is expected to dissipate in a couple of days east of Portugal.